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MG Midget and Sprite Technical - front wheel bearings

Some of you know that I have been working on this for several months. Thought it was going to be finished a long time ago and it still is not. Would you believe that some of the bearings recommended by others, and by myself, have been discontinued. So I still have some work to do. But I think what I have found to this time is important enough to post.

After looking at what I have found I would appreciate any solutions or sources for bearings that actually fit. I say after looking at what I have found simply because this has become big enough of a project with out spending more time on things already covered. I hope you understand.

So, here it is. http://smithtr6.com/bearings.htm

I did the text this morning so please forgive typing and grammatical errors. Just let me know of any glaring ones so I can correct them.

Just one other thing. Contact every bearing company and supplier and raise H*** so they fix this.
tomshobby

Beautiful explanation...
T Dafforn

Hey Tom

I dont know if you remember but you do NOT want to get....

NSK no’s 7303BEAT85SUN and 7205BEAT85SUN

Bearings...These have the pedimite races, Yes they will SORT-A work for our wheel applications but these bearings are designed for super cold applications (aka anti artic) and corrosive chemical enviorments .... thus the the use for the Pedimite races (a hard plastic composite material)

the bearing you want is from KOYO ...Koyo is the wheel bearing that GM uses in all there NEW cars and trucks

Koyo 7303 BGC 3, and Koyo 7205 BGC 3

These bearings have the Brass races, and fall in the mid spec range of what our bearings require with at least 250 degrees ferinhieth on ither side to spare for wheel bearing temps, and have a much higher tension crush wieght ( yeah I cant remember the exact terminaology) agian thats over kill for our midgets...plus the brass has more give (flex) where the piediamite has no give and will crack when force flexed

So its probably a good thing that the Pidiamite 40 degree angular bearing has been discontinued to avoid pitfuls for future spridget wheel bearing buyers


Agian like the others to come ... I have to say the spindle breakage is just not an issue for 95% of spridget people...the only timethis seems to be an issue is high speed, hard turning/braking type driving...on this board thats about 4 people that has to give thought....the rest of us even auto-cross racers really dosent apply...its to rare an event and is probably more likely "rachmacb", would slide off a mountian during a snow storm in IOWA on Aug. 18th then for one of us to break a spindle driving down the road...even if Arie was in a car chase agianst the cops

But your artical is well researched out, and I like the work you have done on shims, thats vary involved


Try this bearing dealership...I found them vary helpful

ibtinc.com


Prop
Prop

Thanks Prop,

I appreciate your comments.

I will follow up on your suggestions tomorrow.

Tom
tomshobby

Tom,

Several people here on the BBS are building a wiki data base (Im not that computer savey to know what that meanss)....I think robert and monty who specializes in prichards and lehnmans maybe part of that adventure.

I really think your artical on wheel bearings and shims needs to be apart of the wiki project. you have certianly got a specialtiy that can be of great assistance to others. esp. as time marches on and these bearings are sourced and enginered in the grand land of china

Prop...With electronic ignition, our little 8 year old china girl that makes ALL our condensers now makes our wheel bearings
Prop

Prop, thanks for the lead. I found a list of about 75 bearing manufacturers on the site and have already contacted about 30 of them.
ONE has responded that they might be able to help and I am going to call them later today.
But I still have about 40 companies on my contact list.
I contacted one company in England and let them know it would be nice for a British company to produce bearings for these cars.
tomshobby

Tom

If you have an IBT store close by, They may have an engineer on staff, I live in a town of 40K and our local IBT store does have a full time engineer (and can talk to the common man..LOL)....But that maybe due to I live in farm country ...But Id think wisconsin isnt exactly ..... "new York CITY!"


Prop
Prop

Tom

Thanks!

Dave
Dave Rhine ('78 1500)

Prop,
Your suggestion led to this.

"Tom -
I did not read your full document for technical accuracy or completeness but it would seem that you fully understand what you are trying to do and the technical implications of your choices. Your analysis is sound.

You have identified multiple ways of 'fixing' the problem and you understand that, short of having the correct bearing, all of these methods have their problems in that they introduce more complexity into
an already complex assembly. You recognize that the more parts there are the more potential for error there is.

To have a custom bearing made is one solution and another would be to make a new axle with the radius of the available bearings as you identified in your summary. A new axle with a smaller radius will create a stress point that did not exist before so a change in material or other metal process may be required also.

Sue is correct that EDT does not have the product that you need but Jeff at LMS will either be able to assist you or he will be able to make another referral to get you pointed in the right direction.

You are most of the way to solving the problem because you have it identified but I wish you the best in your search for the right product.

It is always nice to see that someone takes care of the legacy cars on the road.

Have a good evening.

Carl Klinge
Engr Mgr
EDT Corp"

I contacted Jeff this afternoon and am waiting for a response. Maybe, just maybe........
tomshobby

Hi Tom
Tom IMO you are confusing the issue too much.

The way I see it there are 2 main problems.

The first is that the original bearing speck called for face adjusted bearings, the modern equivelent is not face adjusted and so is therefore no use. However a modern equivelent that is face adjusted is available and will therefore correct that problem. All the other bearings you have listed do not cure this first problem so IMO are not candidates.

The second problem was that the original spec called for a large radius on the inner race of the in board bearing. This is a real problem because no modern bearing of any description has this large radius so we have nothing on the market.

Considering most front wheel bearings have been changed for bearings that are less than correct we ought to see many failures if the second problem was a big deal, however we do not! so is it a problem at all? certainly the bearings are not butted correctly against the alxle but are not failing! The only problem hat is causing an issue is with non face bearing we get too much play in the wheel and so here in the UK our cars fail test. Using face adjusted bearings solves that problem for us.

Therefore again in my opinion axles that fail I believe fail because of the twisting action caused when either taper rollers are fitted too tight when not used with a spacer or normal 20 degree replacement bearings are used and the spacer is machined to remove play but is done too much and again twists the axle.

I think for those who want a perfect fit should use the face adjusted bearing with a suitable 1 mm spacer fitted in board, however I personally do not think the spacer is absolutely necessary and mine do not have anything fitted (As don't hundreds of others) but the spacer would be the final answer.
Robert (Bob) Midget Turbo

Hi Robert,

We agree about the fact that those bearings are not candidates. I was trying to show why they are not.

I also realize that there are face adjusted bearings available. I found some 40-degree angular contact bearings that are "flush" ground.

I also agree that they would be fine with the shim. But it would be better if a shim was not required.

We don't agree about the effect of having a space between the bearing and stub face. And that disagreement is not a bad thing in any way that I can see.

While contacting about 70 bearing companies I have found 2 of them that may be able to provide bearings that fit correctly without shims. This tells me that I did not totally waste my time.

tomshobby

I understand that Tom but do you seriously believe that someone will tool up to make a bearing that they may sell 1000 of? You have infinitely more faith than me.. Or have you got a 1000 bucks for a bearing?

Waiting with baited breath
Robert (Bob) Midget Turbo

Well, at least someone's trying to address the problem!

If there's no resolution to the problem, then so be it.

Thanks for trying Tom

Dave
Dave Rhine ('78 1500)

Bob, In 1992, when I was in my mid forties I went back to college. One of the courses I took was to learn a CAD/CAM program. It happened that the software company held an international annual "Wildest Part" contest. I designed and made a part for entry. It was an extreme challenge for several reasons. One was that the software was not designed to do the kind part I was working on. Another was that the CAD lab was on the upper floor and I had to go up and down the stairs countless times over the months I was working on this project. Having a disability the steps were a challenge. My fellow students often tried to get me to quit because they saw how difficult it was for me. I entered my work and was not allowed to compete in the student category because I was teaching part-time. The prize was a $12,000 CAD/CAM software package.

I used that software to produce the drawings I used in my web page. And the company used things I discovered about their software to make improvements in it.

I tell this so you can understand that if there is any way for us to have the correct bearings I will find it.

And, I welcome you or anyone else that wants to join me in the search.
tomshobby

Tom,

Now You truly have me fasinated!

Please dont think Im demeaning you, I think each of us on this BBS boared has a specialty of some type when it comes to the midget, some more unique then others

But seriously, Why wheel bearings, not that there is anything wrong with that field, I mean your pushing 60, you have engineeering skills..Did something happen with a spindle that you had envolvement with, trust me Ive been there, when my cranksaft broke it did have an effect on me to try and understand "WHY" and how to make it stronger if not better...And embarresingly I have to admit 18 months later, Im still thinking about that stupid crankshaft.

Like I said, I find you interesting to choose wheel bearings as ones mission in life for the cause of MG midget, Granted they fasinated me to, but my main motivation was to figure out how to get the newest coolest idea in bearings without paying the $600 price tag of the 40 degree angular bearings...but your motivation Im stumped by.

Prop
Prop

Prop,

Actually I am on the other side of 60.

So, how this started. I purchased my Midget in pieces. The PO was about mid way on a complete restoration and gave up. He happened to be at the wheel bearing place. This was last summer and even though I had my first Triumph in '65, I had never even taken notice of a Midget much less seen one in boxes.

When I got to the point of installing my freshly rebuilt calipers I found the rotors rubbed in them. One thing led to another and I realized it was a bearing problem causing the rub. As I began looking for bearings I came to the realization that there did not seem to be any that fit correctly.

As I began my search suppliers and bearing companies continually recommended bearings that did not fit correctly. The responses and non-responses I received and the general attitude of "we just don't care so buy what we have or go without" fed my determination.

As far as $1,000 or $600 bearings, I have discovered a possibility very, very much less costly. Just checking out a couple other possibilities before letting it out.

I would have no problem whatsoever fitting bearings to my car. But that is not my "why"

This is my "why". I am searching for a solution so every owner of a Midget or Sprite can readily obtain correct replacement bearings for their car. Bearings that simply fit properly.

And don't worry, I have other projects.

tomshobby

Not sure I understand the comments of Dave R, are you getting at me Dave? I have I believed done my fair share to sort Spridget front wheel bearing problems and have spoke with Tom on numerous occasions. I simply suggested that hoping a company would make a very limited run of specialist bearings was a very forlorn hope IMO. However with bearings costing around a dollar to manufacture maybe someone will come through.

By the way Dave if you want an ultimate solution then fit a face adjusted bearing pair and use a 1mm spacer on the inboard bearing then you have the perfect answer. All Tom is trying to do is find a solution to avoid using the spacer (Although thousands are not presently using a spacer with no apparent problems) I merely said I think he is hoping for the impossible but would wait with baited breath, not sure that deserved flaming?
Robert (Bob) Midget Turbo

Bob

No offense intended.

I should have said: "Thanks for trying Tom & Bob".

I know you both have worked on this problem extensively & I appreciate both of your efforts!

I've followed the threads since they first started with keen interest, since I have also replaced my wheel bearings & scratched my head wondering what I did wrong.

If you took it wrong, well then, that's you.

No offense intended.

Dave
Dave Rhine ('78 1500)

Thanks understood. :)
Robert (Bob) Midget Turbo

Your welcome...
Dave Rhine ('78 1500)

Oh come on, get a room love birds...we want to see blood....LOL
Prop

Please correct me if I'm off base here. The problem arises from the axle not having the correct radius machined into it. Would it be possible to grind a new bigger radius taking a small amount of material off of the large diameter area where the seal sits? Is this a simple operation?
the axles have center holes machined into them. Can they be reused to set up the axle. If this is possible a rebuilder could machine the axles for a fee and any bearing of the correct dimension should work. Yes??? No???
J Bubela

J

Thats seems to be the genral consensous, Ive seen reports where some people grind the bearing, and others have ground the housings

But I wonder how many just put the bearings in and just torque the thing down into place and never give a 2nd thought.

Prop
Prop

J, I also have been working with Tom and others on the problems recently encountered and there are two problem areas that we have identified. One is that the radius on the inner bearing ID isn't sufficent to clear all the known variations in radius between the spindle and the swivel axle portion which is necessary to reduce stress between those parts. The second is that there are ball type bearings being marketed which fit in that area but have incorrect race dimensions to are too loose when torqued down against the spacer and result in MOT failures in GB. The face adjusted bearings address that problem but at a significant increase in cost and from what I understand some of those may have radius interference problems. If the inner bearing doesn't fit up snugly against the swivel axle then the disc is not centered in the caliper and you may have fit problems with new discs and pads as well as reducing the strength factor gained by the original engineers from haveing the effective diameter of the spindle almost doubled by using the two inner races and the spacer to add additional strength to the spindle.
Bill Young

If anyone has wondered why we have this problem, I just received this from KOYO.

Hello Tom,
I have investigated your issue and have found some interesting details that I would like to run past you.
The OEM ball bearing used on the MG 1961 - 1979 was part number 7205 on the inner and 7303 on the outer.
These are angular contact bearings as you stated however the originals had a R measurement of .040 or

Also there was production of these during the same year span that used Tapered Roller bearings 30205 on the inner and 30303 on the outer.
These Tapers also had an R measurement of 0.40.

I have investigated several Bearing Manufacturers specs and find no bearings of this size either ball or Roller that have an R measurement larger the 0.40.


I have read your included link and do believe that the issue is most likely a result of wear on the Spindle and perhaps repair of the spindle is the safest and most easily resolved direction to take.

Please share your thoughts regarding my email .

Best Regards
Arron Muscovich
Automotive Aftermarket Specialist
Koyo Corporation of USA
amuscovich@koyousa.com
tomshobby

So, in other words, we seem to be back where we started!
Dave Rhine ('78 1500)

Tom,

Did you pass on the RHP drawings, maybe the guy missed the fact that the drawings had a 2mm minimum for the critical bearing radius dimension as has happened before. Searching for the RHP bearing reference does give some hits indicating the bearing is an automotive special which makes sense, and indicates that there were a number of other specials about for this bearing. I've played with a couple of Porsche and VW taper roller bearings, for a machining job I did, and both had much larger than normal radii, for an industrial bearing at least, at the same point. That makes sense in the usage due to the increased radius allowing a larger radius for the critical stubaxle radii so reducing the stress concentration there.
David Billington

I don't know what the russian at Koyo is talking about - how does 'spindle wear' come into it ? Don't think he does either.

We have old bearings with much larger radiuses than 1mm radius (40 thou) - assume that what he means ?

Has he seen the pics of the actual bearings - they are not from Mars ! or are they - que Prop !

R.
richard boobier

I just thought a sample of some of the really dumb things I have received would help demonstrate why this all started in the first place and why there is such resistance to fixing the problem.

Like they say, "Ignorance is bliss". And there are a lot of very happy bearing manufacturers and suppliers out there.

AND, no we are at no means back where we started. I believe we are well on the way to a solution.
tomshobby

I hope so, a resolution would benefit ALL Spridget owners.

Dave
Dave Rhine ('78 1500)

Thank you Tom for the article! In Spritely Years page 20, John Sprinzel describes two broken stub axles; one in 1968 another ten years before. “ Ten years had gone by and the same parts were still breaking” 1968!! He had to spend the night in a sheep station but he was not alone. 52 years later you solved the problem.
I am replacing the front wheel bearings because I change to disk brakes. I do have a 7205B-7303B combination with the plastic races. Although I can not measure a difference in radius, in one stub axle there is a gap of less than 0.20 mm and more than 0.15 mm in the other there is no gap. Where can I order the right shims and what is a standard dimension?
Another fact is that the face on the stub axle where the shim comes is not flat but a cone of about 176 degrees. What implications does it have?
Flip



Flip Brühl 948 frog 59

Hi Flip,

Glad the efforts of all of us helped.

McMaster-Carr has shims available. A 1mm thick shim is usually good but yours may need a little more, possibly a .2mm additional. McMaster-Carr also has shims that fit the hub and the bearing spacer if the bearings are tight or loose. (see the "original" diagram in my article)

It also looks like you have a little more going on though. It looks like one or two things is going on.

The first possibility is that the bearing was wobbling causing wear on the spindle face. That would also mean that the bearing would have been locking up so that the inner race was spinning. So you will want to check the spindle diameter where the bearing fits. Also a good idea to check the inside of the hub for bearing fit.

A second possibility is that the spindle was weakening and flexing. I doubt this however because the wear appears to be concentric and more like what would happen in the first explanation.

A third possibility is that someone had this apart and removed some metal for some reason.

Any shimming would have to account for the tapered surface so the bearing would have proper support. Also the hub step perpendicularity would need to be verified and repaired or replace the hub if needed.

At any rate, be sure you know what caused the taper or at least what did not before trusting the axle.
tomshobby

I informed what a ballbearing including making a radius of 3.5 mm costs for a 7205B: €69.-- without 19% BTW (=VAT) so I stick to the shim witch was € 0.13 including BTW. (It took me an hour and 2 liter gasoline up and down the shop…)

Flip
Flip Brühl 948 frog 59

There has been another breakthrough.
Norm Kerr has done the math. Actual numbers now show that the spacer between the bearings does improve the axle strength in both situations of contact or non-contact between the inner bearing and stub face. So, one more question laid to rest.

He also proved that the full contact between the bearing and stub face is strongest.

Flip, thanks for letting us know what you found out.
tomshobby

This thread was discussed between 04/03/2010 and 11/03/2010

MG Midget and Sprite Technical index

This thread is from the archive. The Live MG Midget and Sprite Technical BBS is active now.